Method for measuring stable and reproducible electrode-tissue impedance

1. A method for measuring stable and reproducible electrode-tissue impedance, comprising:

providing a stimulation system including a computer;

software, loaded in the computer, adapted to perform a stimulating method for a visual prosthesis having a plurality of electrodes;

a video processing unit; and

an implanted neuron-stimulator including at least one electrode;

preconditioning the electrode-tissue interface by delivering a first stimulation signal, including charge balanced biphasic square wave current pulses for a duration suitable to precondition the electrode interface to the electrode, the duration being between 1 second and 10 minutes;

stopping preconditioning at the end of the duration;

measuring an impedance on the electrode at similar electrode-tissue interface conditions to the preconditioning step, after said preconditioning step within a predetermined delay;

transmitting the impedance wirelessly to a computer; and

estimating perceptual thresholds based on the impedance.

2. The method for measuring stable and reproducible electrode-tissue impedance according to claim 1 wherein the electrode-tissue impedance is measured in vivo.

3. The method for measuring stable and reproducible electrode-tissue impedance according to claim 1 wherein preconditioning of the electrode-tissue interface is carried out one electrode at a time or in groups of electrodes.

4. The method for measuring stable and reproducible electrode-tissue impedance according to claim 1 wherein preconditioning of the electrode-tissue interface is carried out for all electrodes simultaneously.

5. The method for measuring stable and reproducible electrode-tissue impedance according to claim 4 further comprising varying a combination of variable pulse-width amplitude and frequency is used to control preconditioning of the electrode-tissue interface.

6. The method for measuring stable and reproducible electrode-tissue impedance according to claim 1 , comprising preconditioning at 10-300 μA at 15-120 Hz with 0.1-2.0 ms pulse width.

7. The method for measuring stable and reproducible electrode-tissue impedance according to claim 1 , comprising preconditioning at 30-150 μA at 30-120 Hz with 0.2-1.0 ms pulse width.

8. The method for measuring stable and reproducible electrode-tissue impedance according to claim 1 , comprising: preconditioning at 80-120 μA at 40-60 Hz with 0.4-0.6 ms pulse width.

9. The method for measuring stable and reproducible electrode-tissue impedance according to claim 1 , wherein the step of measure is measuring with charge balanced square wave current pulses.